1. Field of the Invention
The present invention relates generally to wireless communications systems. More particularly, the present invention relates a hybrid cordless telephone system that allows a user to engage in telephonic communication using a data network, such as the Internet, or the publicly switched telephone network (PSTN).
2. Background
As alternatives to the publicly switched telephone network (PSTN), such as cellular telephony and Voice over Internet Protocol (VoIP), become more widely available and accepted, hybrid telephone devices that provides users the ability to communicate using more than one telephone technology become increasingly useful.
In the case of VoIP, also referred to as Internet telephony, for example, users are able to conduct a telephone conversation over a data network, such as the Internet. Using a digital device, such as a computer or Internet telephone, a user's voice is digitized into packets that are transmitted to the called party's telephone over the data network. FIG. 1 is a schematic diagram of a conventional system for carrying out VoIP communications over a data network. A VoIP telephone provides a user access to VoIP communications. VoIP telephone 102 is provided with an analog telephone adapter (ATA) 103 to send and receive digital data carried over the Internet. The caller's voice is received in a microphone of VoIP telephone 102 and digitized for transmission as data packets over a data network 104, such as the Internet. The digitized voice data is received by the called party, who may either employ a traditional telephony device 106, a VoIP telephone 107, or use a device supporting VoIP, such as computer 108.
Using VoIP provides potential advantages for users. For example, because VoIP telephone calls can be made over the Internet, long distance charges can be avoided. Further, because data is carried in packets, service providers may realize savings in bandwidth and other resource usage as compared with circuit-switched communications paradigms such as the PSTN.
VoIP technology can also be used to provide communication between a cordless telephone user and a VoIP network. FIG. 2 illustrates a conventional cordless VoIP telephone system 200. Cordless VoIP telephone system 200 includes a base unit 202 and a handset 204. Base unit 202 includes system microcontroller/router 206. System microcontroller/router 206 sends and receives a VoIP data stream to and from a data network 208 using an analog terminal adapter module 210. ATA 210 provides connectivity to data network 208 through a connector 209, such as RJ45 connector and a modem or other data network connection, such as device 211. A wireless module 212 sends and receives digital data wirelessly to handset 204 through a base antenna 214. Handset 204 is configured with an adapter that can convert a VoIP digital data stream into an analog signal to be played through an earpiece in handset 204 to the user. Handset 204 communicates with base unit 202 using an RF communications protocol (or standard) such as 802.11 or DECT. In this manner, a user of handset 204 can communicate wirelessly to an external telephone number using VoIP technology.
Despite the advantages of these alternative telephone technologies, for many telephone users, it may be desirable to maintain a traditional PSTN line in addition to an alternative telephone technology. For example, the user's Internet connection may not be operating or may not be operating properly making telephonic communication difficult or impossible. As a result, the user may desire to have access to the often more reliable PSTN. In such cases, a hybrid telephone that allows a user the ability to connect to both the PSTN or a data network, such as the Internet, would be desirable.
However, there are a number of challenges associated with a hybrid cordless telephone that allows conventional cordless telephones to engage in telephone communications over a data network or the PSTN. For example, many cordless telephone systems were designed to transmit primarily voice information employing time division multiplexing (TDMA) technologies such as WDCT. Unfortunately, such technologies are not designed to carry high speed data connections that are desirable to support VoIP communications. Similarly, handsets using digital protocols, such as 802.11, are not designed to communicate with an analog link to the PSTN. Consequently, what is required is a hybrid cordless telephone system that allows a user to communicate over a data network or over the PSTN.